It is common in the structure of high intensity lamps to utilize a pressurized inert gas-filled capsule having a long filament and a pair of leads connected from the filament to the lamp base. A prior art lamp 20 is depicted in partially exposed perspective view in FIG. 1. The depicted lamp is used generally in commercial and retail settings to brightly illuminate a particular area such as a store window. A filament capsule 22 is enclosed within a second larger light-transmissive tubular outer envelope 24 that is sealed to the base. The base 26 is a bayonet-style cylindrical enclosure. The lamp 20 is common in European applications and is known as the T or BT style lamp. This lamp operates in the 220-250 volt range. The base is typically constructed of conductive metal, that electrically connects each of the capsule's conductive leads 28 to corresponding contacts in a light fixture socket (not shown). The leads 28 in this example comprise a pair of filament leads 29 that are electrically connected to a pair of base leads 31, which extend upwardly from the base 26 to a point just below the capsule. This configuration provides for easy attachment of the capsule to the base.
It is important to position the capsule 22 appropriately within the light-transmissive portion of the outer envelope 24. It is sometimes also important to position the capsule 22 with respect to base 26. In so positioning the capsule, it may be necessary to extend the leads 28. Since the leads are somewhat smaller in diameter relative to their lengths, they may not have sufficient strength to support the weight of the capsule.
Prior art capsule leads have been supported by surrounding them with a ceramic insert 30 (shown also individually in FIG. 2) that extends from the bottom of the bulb base 26 up to the lower end 32 of the capsule 22. The leads extend along inner, axially-disposed channels 34 in the insert 30. The capsule 22 may be partially seated within preformed indents 36 at the top of the ceramic insert 30. These indents 36 may include recesses for receiving adhesive or cement to permanently seat the capsule in the insert. While the insert 30 satisfactorily isolates the leads 28 and supports the capsule 22, thus preventing bending and twisting of the capsule/lead structure within the lamp, the insert 30 adds substantial weight to the lamp and is prone to chipping from applied shock and vibration. The ceramic insert is also somewhat expensive due to high material and construction costs and, therefore, contributes to higher lamp construction costs.
It is a general object of the present invention to provide improved capsule supports for lamps that utilize filament capsules.
It is a further object of the present invention to provide a light filament support base, particularly adapted for use with sealed filament capsules, that is lower in weight and cost than conventional ceramic inserts and that exhibits durability equal to or greater than ceramic inserts.
It is another object of this invention to provide a light filament support base that can be utilized with existing lamp components with minimal modification thereof.